The Evolution of Blue Stragglers Formed Via Stellar Collisions

Abstract

We have used the results of recent smoothed particle hydrodynamic simulations of colliding stars to create models appropriate for input into a stellar evolution code. In evolving these models, we find that little or no surface convection occurs, precluding angular momentum loss via a magnetically-driven stellar wind as a viable mechanism for slowing rapidly rotating blue stragglers which have been formed by collisions. Angular momentum transfer to either a circumstellar disk (possibly collisional ejecta) or a nearby companion are plausible mechanisms for explaining the observed low rotation velocities of blue stragglers. Under the assumption that the blue stragglers seen in NGC 6397 and 47 Tuc have been created solely by collisions, we find that the majority of these blue stragglers cannot have been highly mixed by convection or meridional circulation currents at anytime during their evolution. Also, on the basis of the agreement between the predictions of our non-rotating models and the observed blue straggler distribution, the evolution of blue stragglers is apparently not dominated by the effects of rotation.

36 pages, including 1 table and 7 postscript figures (LaTeX2e). Also avaliable at http://astrowww.phys.uvic.ca/~ouellet/ . Accepted for publication in AJ

References in corpus (3)

• Evolution of Stellar Collision Products in Globular Clusters -- I. Head-on Collisions
• The Importance of Realistic Starting Models for Hydrodynamic Simulations of Stellar Collisions
• The Evolution of Blue Stragglers Formed Via Stellar Collisions

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• The Distribution of Collisionally Induced Blue Stragglers in the Colour-Magnitude Diagram
• A Spectroscopic Analysis of Blue Stragglers, Horizontal Branch and Turn-Off Stars in Four Globular Clusters
• MODEST-1: Integrating Stellar Evolution and Stellar Dynamics
• Linear nonadiabatic properties of SX Phoenicis variables
• The Formation Rate of Blue Stragglers in 47 Tucanae
• The binary mass transfer origin of the red blue straggler sequence in M30
• Modelling Collision Products of Triple-Star Mergers
• The Evolution of Blue Stragglers Formed Via Stellar Collisions
• A spectroscopic study of the blue stragglers in M67
• Models of Individual Blue Stragglers
• Exotic populations in Globular Clusters: Blue Stragglers as tracers of the internal dynamical evolution of stellar systems